Fix git dependencies prereleases resolution (#1458)

poetry/repositories/repository.py

@@ -64,7 +64,13 @@ class Repository(BaseRepository):
 
         for package in self.packages:
             if name == package.name:
-                if package.is_prerelease() and not allow_prereleases:
+                if (
+                    package.is_prerelease()
+                    and not allow_prereleases
+                    and not package.source_type
+                ):
+                    # If prereleases are not allowed and the package is a prerelease
+                    # and is a standard package then we skip it
                     continue
 
                 if constraint.allows(package.version):

tests/conftest.py

@@ -81,7 +81,7 @@ def mock_clone(_, source, dest):
     parts = urlparse.urlparse(source)
 
     folder = (
-        Path(__file__).parent.parent
+        Path(__file__).parent
         / "fixtures"
         / "git"
         / parts.netloc
@@ -91,7 +91,6 @@ def mock_clone(_, source, dest):
     if dest.exists():
         shutil.rmtree(str(dest))
 
-    shutil.rmtree(str(dest))
     shutil.copytree(str(folder), str(dest))
 
 

tests/fixtures/git/github.com/demo/prerelease/pyproject.toml

+[tool.poetry]
+name = "prerelease"
+version = "1.0.0.dev0"
+description = "Some description."
+authors = [
+    "Sébastien Eustace <sebastien@eustace.io>"
+]
+license = "MIT"
+
+# Requirements
+[tool.poetry.dependencies]
+python = "~2.7 || ^3.4"
+
+[tool.poetry.dev-dependencies]

tests/installation/test_installer.py

@@ -1529,3 +1529,31 @@ def test_run_installs_with_url_file(installer, locker, repo, package):
     assert locker.written_data == expected
 
     assert len(installer.installer.installs) == 2
+
+
+def test_installer_uses_prereleases_if_they_are_compatible(
+    installer, locker, package, repo
+):
+    package.python_versions = "~2.7 || ^3.4"
+    package.add_dependency(
+        "prerelease", {"git": "https://github.com/demo/prerelease.git"}
+    )
+
+    package_b = get_package("b", "2.0.0")
+    package_b.add_dependency("prerelease", ">=0.19")
+
+    repo.add_package(package_b)
+
+    installer.run()
+
+    del installer.installer.installs[:]
+    locker.locked(True)
+    locker.mock_lock_data(locker.written_data)
+
+    package.add_dependency("b", "^2.0.0")
+
+    installer.whitelist(["b"])
+    installer.update(True)
+    installer.run()
+
+    assert len(installer.installer.installs) == 2